1. Field of the Invention
The present invention relates to a high-frequency module and, in particular, to a high-frequency module including a multilayer substrate having a resistor and a coil disposed therein.
2. Description of the Related Art
In recent years, wireless apparatuses, such as cell phones and wireless LANs (Local Area Networks) have become highly functional and the sizes of the wireless apparatuses have been decreased. Among such highly functional apparatuses, a wireless apparatus that can handle signals in a plurality of frequency bands has been developed. In order to decrease the size of the wireless apparatus that can handle signals in a plurality of frequency bands, a wireless module has been developed into which some of the parts of a wireless system, in particular, front-end parts are integrated as one package.
For example, Japanese Unexamined Patent Application Publication No. 2000-349586 describes an antenna duplexer that includes two duplexers and a connection terminal group for connecting the duplexers to external circuits. The connection terminal group includes an antenna terminal sub-group for connecting the duplexer to an external antenna and a transmission terminal sub-group and a reception terminal sub-group for connecting the duplexer to an external circuit. In this antenna duplexer, in a plane, an area in which the antenna terminal sub-group is disposed and an area in which the transmission terminal sub-group and the reception terminal sub-group are disposed are separated so as not to cross each other. The antenna duplexer includes an antenna terminal for an 800 MHz band and an antenna terminal for a 1.9 GHz band. The antenna terminal sub-groups are disposed close to each other in the vicinity of one side of a rectangular shape in plan view. It is described in Japanese Unexamined Patent Application Publication No. 2000-349586 that the size of this antenna duplexer which unifies two duplexers in one package can be decreased while maintaining an excellent frequency characteristic. Also, it is described that manufacturing of this antenna duplexer can be facilitated.
In the antenna duplexer described in Japanese Unexamined Patent Application Publication No. 2000-349586, two antenna terminals corresponding to two different frequency bands are disposed on the surface of the antenna duplexer along one side of the rectangular shape in a plane. In such an antenna duplexer, the physical distance between the two antenna terminals corresponding to different frequency bands is small, and therefore, the separation characteristics (isolation characteristics) between the two antenna terminals deteriorates. That is, crosstalk occurs between the antenna terminals and noise is induced.
Additionally, since the distance between a plurality of antenna terminals is small, the physical distance between wirings connected to the individual antenna terminals in the module substrate is small. Accordingly, the separation characteristics between the wirings in the module substrate deteriorate. Thus, crosstalk occurs between the wirings.
Furthermore, the wirings in the module substrate are arranged so as to extend in a direction perpendicular to a side of an area where the antenna terminals are formed. Accordingly, the directions in which the wirings connected to the individual antenna terminals extend are substantially parallel to each other. Thus, crosstalk between the wirings in the module substrate easily occurs.
Still furthermore, the above-described antenna duplexer is disposed on a surface of a module mounting substrate, such as a printed circuit board. The antenna terminals are connected to terminals formed on the module mounting substrate by means of, for example, solder. At that time, the physical distance between wirings formed on the surface of the module mounting substrate becomes small, and therefore, the separation characteristics deteriorate.